The present invention relates to a process for dyeing cellulose fibers or its union fibers which is effected according to an exhaustion dyeing method using a reactive dye containing at least one s-triazinyl group having a group of the formula: ##STR2## wherein M represents a hydrogen or an alkali metal, in an aqueous dyeing bath having a pH in the range of 4 to 10 and a dyeing temperature in the range of 95.degree. C. to below 150.degree. C. In dyeing cellulose fibers by an exhaustion dyeing method using reactive dyes which can be bound with the cellulose fibers, such as those containing reactive groups, for example, dichlorotriazinyl, monochlorotriazinyl, monofluorotriazinyl, fluorochloropyrimidinyl, dichloroquinoxazinyl, methylsulfonylpyrimidinyl, vinylsulfonyl or sulfatoethylsulfonyl groups, the pH of the dye bath is controlled generally to 10 or above by incorporating an acid binding agent or a substance which releases the acid binding agent upon heating, such as sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, sodium metasilicate, trisodium phosphate, tripotassium phosphate, potassium pyrophosphate, sodium pyrophosphate, sodium bicarbonate or sodium trichloroacetate, either alone or in the form of a suitable mixture thereof. The dye bath further contains an electrolyte such as sodium chloride or sodium sulfate and the dyeing temperature is 100.degree. C. or below.
In dyeing union fibers of cellulose and other fibers, particularly cellulose/polyester blends, with the above-mentioned reactive dyes, the dyes are used in combination with disperse dyes. In dyeing these blends with the two classes dyes in one step, several problems are raised. For example, the acid binding agent or a substance which releases acid binding agent required when the reactive dyes are used have defects that they coagulate or decompose various disperse dyes and the acceleration of hydrolysis of the reactive dyes is caused in an aqueous medium at a high temperature of, for example, 130.degree. C. required in dyeing polyester textile materials. Whereby satisfactory results cannot be obtained. Therefore, in dyeing such cellulose/polyester blends, a two-bath method has been employed generally wherein one portion of the cellulose or polyester in the blends is first dyed and second the other fiber is dyed using another bath.
In dyeing cellulose/wool blends with the above-mentioned reactive dye and acid dye, a decontaminating agent is used, since the acid binding agent or the substance which releases the acid binding agent used for obtaining a pH of the dye bath suitable for fixing the reactive dye on cellulose damages the wool. The dyeing is effected by a one-bath or a two-bath process using the direct dye and acid dye.
In dyeing cellulose/polyacrylonitril blends, a two-bath method is employed using the reactive dye and basic dye or cationic dye or a one-bath two-step process wherein a anti-precipating agent is used is employed.
The present invention relates to an improvement in or relating to these dyeing methods.
It is known from the specification of Japanese Patent Publication No. 24323/1975 that a reactive dye containing an s-triazinyl group having a quaternary nitrogen atom derived from nicotinic acid is used for the exhaustion dyeing in the presence of an acid binding agent at a low temperature of 35.degree. C. to 40.degree. C.